Hypsipyla Shoot Borers of Meliaceae in Sri Lanka - Australian ...

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infestation coincided with the wet season, rendered their use economically and environmentally unfeasible. Some systemic compounds (e.g. monocrotophos and azinphos methyl) provided limited control but were generally ineffective. For further details refer to Wylie (these Proceedings). Silvicultural control Concern regarding the unregulated exploitation of T. ciliata in natural forests led to attempts to grow the species in plantations. Most trials have been small scale (less than 0.5 ha), unreplicated, carried out on variable sites, and include treatments that vary during the course of the experiment. In addition, the interval between observations was often long, and records of damage were not consistent. Shoot damage from H. robusta represents the major but not the only limitation to growth of T. ciliata. Trees were also damaged by the elephant beetle, Xylotrupes gideon (Linnaeus) (Coleoptera: Scarabaeidae), especially in northern Queensland and are occasionally seriously defoliated by Pingasa chlora (Stoll) (Lepidoptera: Geometridae). The species is very susceptible to frost and generally does poorly in the presence of heavy weed growth. However, it is the high incidence and severity of damage from H. robusta that has largely precluded commercial growing of T. ciliata. Natural regeneration Early observations revealed that T. ciliata regenerates rapidly in gaps and clearings that occur naturally in the forest or created during logging operations. Trials encouraging natural regeneration demonstrated that seedling survival rather than seed production or germination was the critical stage in early establishment of T. ciliata. Trees require good soils, adequate moisture and ample overhead light, to achieve highest rates of establishment and growth. Growth was fastest in areas receiving both overhead and lateral light following brushing of the undergrowth and opening of the canopy. Heavy thinning of the canopy can lead to higher mortality due to desiccation, mammal browsing, frost, fire and competition from regrowth species. The timing of silvicultural treatment is critical to the success of natural regeneration. Establishment is likely to be optimised under quite intensive site preparation in two main stages. Firstly, the canopy needs to be opened up well in advance of seed spotting or seed fall to avoid smothering of young plants by falling debris from recently treated overstorey (ATH115). Secondly, brushing and treatment of undergrowth are necessary as soon as possible before 52 seed fall or seed sowing to allow seedlings to establish in advance of the regrowth. Enrichment plantings Toona ciliata grew well in enrichment plantings (Haley 1954; Keys and Nicholson 1982; Queensland Department of Forestry 1983a). Planting into relatively small gaps or along cleared lines with lateral shade provided some protection from H. robusta damage during early growth. The gaps must be sufficiently large to remain open during the early growth of the tree, but not so large that they increase susceptibility to damage from H. robusta or allow proliferation of weeds and regrowth species which may smother young trees. Cleared plots may also be susceptible to falling debris from thinning operations and plantings are likely to require continued canopy management throughout their life. The high costs associated with enrichment techniques have limited their adoption as general management practice in Australia (Nicholson et al. 1983; Queensland Department of Forestry 1983b). Silvicultural operations opening up the overstory to encourage growth of T. ciliata are not only expensive but also risky to the under-plant trees which may be damaged during thinning. Growth in existing plantations A number of plantings were established to assess the growth of T. ciliata within existing plantations as an interplanted or underplanted species or through natural regeneration. Cover or companion species assessed were: • Araucaria cunninghamii Aiton ex D. Don Hoop Pine • Grevillea robusta Cunn. ex R. Br. Southern Silky Oak • Flindersia brayleyana F. Muell. Queensland Maple • Agathis robusta (C. Moore ex F. Muell.) Bailey Kauri Pine • Cedrela odorata L. Spanish Cedar • Paraserianthes falcataria (L.) • Eucalyptus grandis Hill ex Maiden Flooded Gum • Eucalyptus pellita F. Muell. Red Mahogany • Eucalyptus saligna Smith Sydney Blue Gum • Zea mays L. Maize Some trials demonstrated that T. ciliata performed better when grown beneath a canopy; either levels of H. robusta damage were reduced under cover, or the
growth response and resultant form of the tree was improved. An overhead canopy also provided protection from frost and hail at some sites. Hypsipyla robusta damage was never prevented in any trials and in most sites, trees were damaged within a few years of planting. The success or otherwise of the various plantings depended on the cover crop species. Tree species with a very dense canopy, e.g. A. cunninghamii, failed to allow adequate light to reach T. ciliata under-plants, and thus growth was poor. This problem was less severe with more sparsely-crowned species such as G. robusta, F. brayleyana and A. robusta. Initial growth was generally better, although this often slowed considerably after a few years if no further thinning was carried out. Under a less dense canopy, damage from H. robusta was more of a problem. In many trials the density of the overstory of any particular species had little or no effect on tree performance or damage intensity. Flindersia brayleyana Toona ciliata grew well under F. brayleyana and a mixed stand of the two species was obtained. The technique was not ideal silviculturally because it requires thinning of potentially valuable but currently unmerchantable F. brayleyana stems. Grevillea robusta The growth of T. ciliata under G. robusta was highly variable, but often good, particularly under younger G. robusta aged 0 to 2 years at the time of planting of T. ciliata. Some of these plantings provide the most promising results from underplant trials. Araucaria cunninghamii Araucaria cunninghamii has been the most widely tested of the companion species, but has been unsuccessful. Attempts to establish T. ciliata under A. cunninghamii by planting or through fostering natural regeneration generally failed. Araucaria cunninghamii quickly formed a closed canopy, which did not allow adequate light to reach the T. ciliata trees. Growth was either suppressed from an early age or trees grew to the nearest canopy gap, resulting in bent and useless stems. The canopy required heavy thinning and the creation of large gaps to allow establishment of underplants. The heavy canopy generally failed to prevent damage from H. robusta. When damage was absent, it was probably due to the very poor growth or condition of the plants. 53 Agathis robusta Agathis robusta has a much sparser crown than A. cunninghamii, allowing better survival and growth of underplants. Under this lighter canopy T. ciliata was heavily damaged by H. robusta and developed poor form. Initial growth was good under A. robusta aged six years but later slowed. Natural regeneration under a planting of A. robusta resulted in some useful trees with minimal management, offering potential for further investigation. Other species Plantings in New South Wales beneath E. saligna and E grandis had some success; however, insufficient information was available to fully assess their potential as cover species. Plantings beneath E. pellita, P. falcataria and Z. mays were unsuccessful. In mixed plantings with C. odorata, T. ciliata was consistently the poorer of the two species with respect to height and incidence of H. robusta damage. Open plantings Open plantings of T. ciliata were generally susceptible to damage from H. robusta, desiccation, flooding, frost, weed competition and mammal browsing. Despite these problems, a number of open plantings have performed well in the long term and have produced merchantable trees. The establishment phase of these more successful plantings was poorly documented and trees may have received protection in the early stages of growth, either from an interplanted species which subsequently failed, surrounding forest, or the addition of a fast-growing underplant species shortly after establishment. Improving early growth rates Toona ciliata grows rapidly under optimal conditions. The choice of good sites, manipulation of the overhead canopy, and use of fertilisers and artificial shelters can improve establishment and further encourage early growth. Such techniques reduce the duration for which trees are exposed to H. robusta attack before achieving a straight bole of merchantable length. A series of fertiliser trials in New South Wales in the late 1950s and early 1960s assessed the impact of nitrogen, phosphorus and potassium on growth of T. ciliata and on susceptibility of trees to H. robusta (Forestry Commission of New South Wales 1959, 1961). Trees responded well to application of potassium. The increase in tree vigour did not influence the incidence of H. robusta damage (Campbell 1966).
Page 1 and 2: Hypsipyla Shoot Borers of Meliaceae
Page 3 and 4: Mayhew and Newton (1998) have revie
Page 7 and 8: Table 1. Summary of current and pas
Page 9 and 10: 26° 21° WEST BENGAL (INDIA) PACHA
Page 11 and 12: The only harvesting of Swietenioide
Page 15 and 16: H. robusta. From that time onwards,
Page 17 and 18: successful and is expected to have
Page 19 and 20: them are species of the subfamily S
Page 21 and 22: T. ciliata grows in dry deciduous f
Page 23 and 24: Table 1. Area of forestry plantatio
Page 25 and 26: S. macrophylla and Swietenia mahago
Page 27 and 28: plantings of S. macrophylla, K. sen
Page 33 and 34: Table 1. Major plantation areas and
Page 37 and 38: mixing seedlings of S. macrophylla,
Page 41 and 42: of these species, plantings have be
Page 43 and 44: 45 Table 5. Continued. Description
Page 45 and 46: 47 Table 6. Description of on-going
Page 47 and 48: locations were generally poorer, wi
Page 49: Table 8. Summary of current and pas
Page 53 and 54: Mr David Spolc (University of Queen
Page 55 and 56: Haley, C. 1954. Forestry in Tropica
Page 57 and 58: Gross Domestic Product, a contribut
Page 59 and 60: A number of parasitoids have been b
Page 61 and 62: A Review of Hypsipyla grandella Zel
Page 63 and 64: Table 2. Summary of current and pas

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